...with decent street tires, it's perfectly drivable in the rain, in fact i've been daily driving mine the past couple days in heavy rain...as the owner's manual states, the interior was designed to withstand mild moisture intrusion from time to time, and any water drops on the sills are easily brushed off when i climb in...
...some folks' experiences have varied, but i've done just fine driving topless in the rain, too - as long as i keep moving at a reasonable speed, the wind keeps water out of my car...of course, if you come to a stop at an intersection while topless, you're going to get a little rain in the cockpit, but nothing worrisome as long as it's only a momentary pause during light sprinkles, just like walking outside...